J.B. Liu
,
L.J. Hu
,
Y.T. Wang
,
Z.Q. Liu
,
K. Miao
,
Z.L. Tian
金属学报(英文版)
The transformation behavior and microstructure development in the heat affected zone
(HAZ) of 800MPa grade ultra fine structured steel was investigated. It was found that
the HAZ has intermediate temperature transformation characteristics in a wide range
of cooling rates, with the bainite sheaves consisting of bainite ferrite plates without
carbide precipitation and retained austenite in the fast cooling regime. At relatively
high cooling rates, which corresponded to low heat inputs, the hardness of the simulated
HAZ was above that of the base metal. When the cooling rate was below 9±C/s, the
welding HAZ would have an obvious softening. The analysis of transformation rates
in continuous cooling processes was completed by numerical differential method. The
result indicated that the microstructure transformation rate of the HAZ in 800MPa
grade ultra fine structured steel changed sharply to slow speeds when the cooling time
t8=5 is longer than 7s.
关键词:
ultra fine structured steel
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